SITE OF PROTONATION IN ANILINE AND SUBSTITUTED ANILINES IN THE GAS-PHASE - A STUDY VIA THE LOCAL HARD AND SOFT ACIDS AND BASES CONCEPT

In this paper we address the long standing problem regarding the site for gas-phase protonation in aniline and substituted anilines. Our stu dy reveals that DFT-based reactivity descriptors can reproduce the exp erimentally observed preferable protonation sites. However, it is foun d that the quantity s(k)(-)/s(k)(+), termed ''relative nucleophilicity '' and a measure of ''local polarizability'', produces more reliable r esults than the local softness, s(k)(-). The problem which sometimes a rises in taking s(k)(-)/s(k)(+) as the reactivity. descriptor is also discussed.